1. Field of the Invention
The present invention relates to a polycarbonate resin composition superior in chemical resistance, weather resistance, heat resistance, and low-temperature impact resistance.
2. Description of the Prior Art
Polycarbonate resins are widely used as thermoplastic resins superior in heat resistance and impact resistance. However, their applications have been restricted, because the impact resistance thereof at temperatures of up to 0.degree. C. is low on account of the polymer structure thereof and the impact resistance of molded articles thereof varies largely with the thickness of the articles and by some other reasons. Therefore, various methods have so far been proposed for correcting these drawbacks. For instance, methods of blending ABS resins with polycarbonate resins are disclosed in Japanese Patent Publication Nos. 15225/63, 27579/80, 21530/82, 12300/83, and 46269/83 and Japanese Patent Application Laid-Open Nos. 40536/82, 149938/83, and 12047/82. It is also disclosed in Japanese Patent Publication No. 29308/73 that a composition comprising a polycarbonate resin and a resin containing an acrylate copolymer is superior in weather resistance and craze resistance. While also various methods have hitherto been proposed for improvements of aromatic polycarbonate resins and aromatic polyester resins in mechanical and thermal properties, combinations of only both the resins are inferior in impact resistance and some other properties. Hence, Japanese Patent Publication No. 9435/80 (corresponding to U.S. Pat. No. 3,864,428), for example, has proposed a resin composition comprising an aromatic polyester resin, an aromatic polycarbonate resin, and a butadiene-based graft copolymer. Such a resin composition, although successful to a certain extent in the improvement of impact resistance, has the drawback of being essentially inferior in weather resistance. Japanese Patent Application Laid-Open No. 129246/78 discloses that molded articles superior in weather resistance and impact resistance are obtained from a blend of an acrylate copolymer with an aromatic polycarbonate resin and an aromatic polyester resin, but these molded articles have also the drawback of being inferior in impact resistance at low temperatures.
As stated above, a variety of methods are proposed for modifications of aromatic polycarbonate resins or of aromatic polycarbonate-aromatic polyester resin mixtures, but resins improved thereby in impact resistance may have deteriorated weather resistance and those improved in weather resistance may be insufficient in impact resistance. Thus, none of the improvements proposed up to now provide resins or resin compositions having well-balanced properties as a whole.
On the other hand, there are great expectations of organic materials in the automotive, electronic, and electrical fields, that is to say, there are needs for organic materials having higher functions and for diversified organic materials different in function. Particularly for automotive exterior applications and the like, where mostly metals have so far been used, there is demand for a resin which is satisfactory in impact resistance, weather resistance, heat resistance, etc. However, such demand has not been fulfilled so that the use of resins is restricted today for applications where it is required for resins to exhibit high performance characteristics under harsh environmental conditions.